Update design_specification.md

First draft of the design specification.

Accept request when completed:
#### Criterion 1: Overview
* [x] Project description
* [x] Design relevance
* [x] Goals and objectives
* [x] Constraints

#### ~~Criterion 2: Methodology~~
* [x] Programming languages
* [x] Development
* [x] Version Control
* [x] Collaboration tools

#### Criterion 3: Architecture
* [x] System
* [x] Data
* [x] Program design

#### Criterion 4: Testing
* [x] Type and purpose of testing to be done
* [x] Performance constraints

#### ~~Criterion 5: Team Roles~~
* [x] Roles and responsibilities of each team member
* [x] A simple breakdown of primary and secondary tasks for each person.

#### Criterion 6 Design Cohesion
* [ ] Mapping of core concepts used in design, to practical implementations in the project
* [ ] Consolidating results with logical validation testing